Abstract: A predominantly beta-phase NiAl overlay coating for use as an environmental coating or a TBC bond coat for articles used in hostile thermal environments, such as components of a gas turbine engine. The coating contains up to about 4 atomic percent hafnium, such as in excess of 1.0 atomic percent hafnium. The coating may also contain about 2 to about 15 atomic percent chromium.

Abstract: A thermal barrier coating (TBC 26) and method for forming the TBC (26) on a component (10) characterized by a stabilized microstructure that resists grain growth, sintering and pore coarsening or coalescence during high temperature excursions. The TBC (26) contains elemental carbon and/or a carbon-containing gas that increase the amount of porosity (32) initially within the TBC (26) and form additional fine closed porosity (32) within the TBC (26) during subsequent exposures to high temperatures. A first method involves incorporating elemental carbon precipitates by evaporation into the TBC microstructure. A second method is to directly incorporate an insoluble gas, such as a carbon-containing gas, into an as-deposited TBC (26) and then partially sinter the TBC (26) to entrap the gas and produce fine stable porosity within the TBC (26).

Abstract: A thermal barrier coating, or TBC (26), and method for forming the TBC (26). The TBC (26) is formed of a thermal-insulating material that contains yttria-stabilized zirconia (YSZ) alloyed with at least a third oxide. The TBC (26) is formed to also contain elemental carbon, and may potentially contain carbides and/or a carbon-containing gas that forms from the thermal decomposition of carbon. The TBC (26) is characterized by lower density and thermal conductivity, high temperature stability and improved mechanical properties. To exhibit the desired effect, the third oxide is more particularly one that increases the lattice strain energy of the TBC microstructure as a result of having an ion size that is sufficiently different than a zirconium ion.

Abstract: A thermal barrier coating (TBC) for a component intended for use in a hostile environment, such as the superalloy turbine, combustor and augmentor components of a gas turbine engine. The TBC is formed of zirconia that is partially stabilized with yttria (YSZ), preferably not more than 3 weight percent yttria, and to which one or more additional metal oxides are alloyed to increase crystallographic defects and lattice strains in the TBC grains and/or form precipitates of zirconia and/or compound(s) of zirconia and/or yttria and the additional metal oxide(s), the inclusion of which reduces the thermal conductivity of the YSZ to levels lower than conventional 6-8% YSZ. Improvements are particularly contemplated for TBC having a columnar grain structure, such as those deposited by EBPVD and other PVD techniques.

Abstract: A protective overlay coating for articles used in hostile thermal environments, and particularly for use as a bond coat for a thermal barrier coating deposited on the coating. The coating is predominantly beta-phase NiAl into which a platinum-group metal is incorporated, yielding a coating system capable of exhibiting improved spallation resistance as compared to prior bond coat materials containing platinum, must notably the platinum aluminide diffusion coatings. A preferred composition for the beta-phase NiAl overlay coating further contains chromium and zirconium or hafnium.

Abstract: A gas turbine engine component includes a perforate metal wall having pores extending therethrough. The wall has a first surface covered by a thermal barrier coating. The pores have first ends which are covered by the thermal barrier coating, and the pores are ventilated from an opposite second surface of the wall for cooling the thermal barrier coating.

Abstract: An article such as a gas turbine blade or vane has a superalloy substrate, and a coating system deposited on the substrate. The coating system includes a protective layer overlying the substrate, and, optionally, a ceramic thermal barrier coating layer overlying the bond coat. The protective layer has an uppermost layer with a composition including platinum, aluminum, and, in atom percent, from about 0.14 to about 2.8 percent hafnium and from about 2.7 to about 7.0 percent silicon, with the atomic ratio of silicon:hafnium being from about 1.7:1 to about 5.6:1.

Abstract: A nickel-base superalloy article has a protective layer on a surface of the substrate. The protective layer has a composition including nickel, aluminum, and at least two modifying elements selected from the group consisting of zirconium, hafnium, yttrium, and silicon. The protective layer is preferably predominantly beta (&bgr;) phase NiAl composition. Each of the modifying elements which is present is included in an amount of from about 0.1 to about 5 percent by weight of the protective layer in the case of zirconium, hafnium, and silicon modifying element, and in an amount of from about 0.1 to about 1 percent by weight of the protective layer in the case of yttrium modifying element.

Abstract: An article protected by a thermal barrier coating system is fabricated by providing an article substrate having a substrate surface, and thereafter producing on the substrate surface a protective coating having a polished, pre-oxidized protective coating surface. The protective coating is produced by depositing the protective coating on the substrate surface, the protective coating having a protective coating surface, thereafter polishing the protective-coating surface, and thereafter controllably oxidizing the protective-coating surface. The protective-coating surface may optionally be controllably roughened by grit blasting after polishing and before controllably oxidizing. A thermal barrier coating may be deposited overlying the polished, pre-oxidized protective-coating surface.

Abstract: A process for casting and preparing an ingot of a beta-phase NiAl-based material, particularly for use in PVD coating processes. The method entails melting a nickel-aluminum composition having an aluminum content below that required for stoichiometric beta-phase NiAl intermetallic so as to form a melt that includes nickel and Ni3Al. Aluminum is then added to the melt, causing an exothermic reaction between nickel and aluminum as the melt equilibrium shifts from Ni3Al to NiAl. However, the aluminum is added at a rate sufficiently low to avoid a violent exothermic reaction. The addition of aluminum continues until sufficient aluminum has been added to the melt to yield a beta-phase NiAl-based material. The beta-phase NiAl-based material is then solidified to form an ingot, which is then heated and pressed to close porosity and homogenize the microstructure of the ingot.

Abstract: An article protected by a protective coating system is fabricated by providing an article substrate having a substrate surface; and thereafter producing a protective coating having a flattened, pre-oxidized protective-coating surface on the substrate surface by depositing a protective coating on the substrate surface, the protective coating having a protective-coating surface, processing the protective coating to achieve a flattened protective-coating surface, and controllably oxidizing the protective-coating surface. A thermal barrier coating may be deposited overlying the flattened, pre-oxidized protective coating.

Abstract: A process for casting and preparing an ingot of a beta-phase NiAl-based material, particularly for use in PVD coating processes. The method entails melting a nickel-aluminum composition having an aluminum content below that required for stoichiometric beta-phase NiAl intermetallic so as to form a melt comprising nickel and Ni3Al. Aluminum is then added to the melt, causing an exothermic reaction between nickel and aluminum as the melt equilibrium shifts from Ni3Al to NiAl. However, the aluminum is added at a rate sufficiently low to avoid a violent exothermic reaction. The addition of aluminum continues until sufficient aluminum has been added to the melt to yield a beta-phase NiAl-based material. The beta-phase NiAl-based material is then solidified to form an ingot, which is then heated and pressed to close porosity and homogenize the microstructure of the ingot.

Abstract: A protected article includes a substrate, such as a nickel-base superalloy, a protective coating comprising aluminum overlying a surface of the substrate, and an iridium-containing oxygen barrier layer overlying the protective coating. A ceramic thermal barrier coating may overlie the protective coating and the oxygen barrier layer.

Abstract: A PVD process and apparatus (120) for depositing a coating (132) from multiple sources (110,111) of different materials. The process and apparatus (120) are particularly intended to deposit a beta-nickel aluminide coating (132) containing zirconium, hafnium, yttrium and/or cerium, whose vapor pressures are sufficiently lower than NiAl to require a different evaporation rate in order to achieve higher deposition rates and better control of the coating chemistry. The PVD process and apparatus (120) entail feeding at least two materials (110,111) into a coating chamber (122) and melting the materials (110,111) at different rates to form separate molten pools (114,115) thereof. Articles (130) to be coated are suspended within the coating chamber (122), and transported with a support apparatus (118) relative to the two molten pools (114,115) so as to deposit a coating (132) with a controlled composition that is a mixture of the first and second materials (110,111).

Abstract: The present invention provides a process for forming active convection cooling micro channels within or adjacent to a bond coat layer applied to a turbine high pressure turbine airfoil. When placed adjacent or within a porous TBC, the micro channels additionally provide transpiration cooling through the porous TBC. The micro channels communicate directly with at least one cooling circuit contained within the airfoil from which they receive cooling air, thereby providing direct and efficient cooling for the bond coat layer. Because the substrate includes an actively cooled flow path surface region that can reduce the cooling requirement for the substrate, the engine can run at a higher firing temperature without the need for additional cooling air, achieving a better, more efficient engine performance. In one embodiment, a metallic bond coat is applied to an airfoil.

Abstract: A thermal barrier coating (TBC) for a component intended for use in a hostile environment, such as the superalloy turbine, combustor and augmentor components of a gas turbine engine. The TBC is formed to contain small amounts of alumina precipitates dispersed throughout the grain boundaries and pores of the TBC to getter oxide impurities that would otherwise allow or promote grain sintering and coarsening and pore coarsening, the consequence of which would be densification of the TBC and therefore increased thermal conductivity. If sufficiently fine, the precipitates also serve to pin the grains and pore boundaries of the TBC, the effect of which is to reduce the tendency for the microstructure of the TBC to sinter, coarsen and undergo pore redistribution, which also increase thermal conductivity of the TBC 26.

Abstract: An article protected by a thermal barrier coating system includes a substrate having a substrate surface, and a thermal barrier coating system overlying the substrate. The thermal barrier coating system has a thermal barrier coating formed of a thermal barrier coating material arranged as a plurality of columnar grains extending generally perpendicular to the substrate surface and having grain surfaces. A sintering inhibitor is within the columnar grains, either uniformly distributed or concentrated at the grain surfaces. The sintering inhibitor is lanthanum oxide, chromium oxide, and/or yttrium chromate, mixtures thereof, or mixtures thereof with aluminum oxide.

Abstract: An article having a protective coating is fabricated by providing an article substrate having a substrate surface; and thereafter producing a flattened protective coating on the substrate surface. The step of producing the flattened protective coating includes the steps of depositing a protective coating on the substrate surface, the protective coating having a protective-coating surface, and processing the protective coating to achieve the flattened protective-coating surface. The protective coating is thereafter optionally controllably oxidized. The article substrate and protective coating have an average sulfur content of less than about 10 parts per million by weight at depths measured from the protective-coating surface to a depth of about 50 micrometers below the protective-coating surface.

Abstract: An article protected by a protective coating system is fabricated by providing an article substrate having a substrate surface; and thereafter producing a protective coating having a flattened, pre-oxidized protective-coating surface on the substrate surface by depositing a protective coating on the substrate surface, the protective coating having a protective-coating surface, processing the protective coating to achieve a flattened protective-coating surface, and controllably oxidizing the protective-coating surface. A thermal barrier coating may be deposited overlying the flattened, pre-oxidized protective coating.

Abstract: An article protected by a thermal barrier coating system is fabricated by providing an article substrate having a substrate surface, and thereafter producing on the substrate surface a protective coating having a polished, pre-oxidized protective coating surface. The protective coating is produced by depositing the protective coating on the substrate surface, the protective coating having a protective coating surface, thereafter polishing the protective-coating surface, and thereafter controllably oxidizing the protective-coating surface. The protective-coating surface may optionally be controllably roughened by grit blasting after polishing and before controllably oxidizing. A thermal barrier coating may be deposited overlying the polished, pre-oxidized protective-coating surface.